None. Somebody else does the screwing for 'em.
TRICK QUESTION. THEY CAN'T CHANGE ANYTHING.
Three. One to do it, one to complain that it has already been done before, and one to repost this joke.
Wanna go ride a bike?
None... they live an ascetic lifestyle and prefer to not use electricity.
Zero. Somebody already did it.
Somebody told him to get a long little doggy.
When do we want 'em? Time machines!
Nothing, you already told 'em twice.
